Apparatus for box crimping synthetic yarns



sept. 1, 1970 J. J. MERTENS 3,526,023

APPARATUS FOR BOX CRIMPING SYNTHETIC YARNS Filed Aug. 9, 1968 INVENTOR JOHAN JACQUES MERTENS ATTORNEYS United States Patent O 3,526,023 APPARATUS FOR BOX CRIMPING SYNTHETIC YARNS Johan J. Mertens, Rozendaal, Netherlands, assignor to Algemene Kunstzijde Unie, N.V., Arnhem, Netherlands, a corporation of the Netherlands Claims priority, application Netherlands, Ang. 18, 1967,

6711372 Filed Aug. 9, 1968, Ser. No. 751,399 Int. Cl. D02g 1/12 U.S. Cl. 28-1.7 2 Claims ABSTRACT OF THE DISCLOSURE A method for box-crimping synthetic yarn which comprises forcing a yarn into one end of a stuffer box against a wad of the yarn already crimped within the box, crimping the yarn at the stufng pressure found within the box, discharging crimped yarn from the wad of yarn at the other end of the box, and simultaneously applying a counter-pressure to the wad of yarn that acts in a direction opposite to the direction of travel of the yarn from the box so that the stuiiing pressure within the stuffer box'remains substantially equal to a desired value.

The apparatus for carrying out this method includes a stuter box, a pair of driven feed rollers for forcing a yarn into the box, and a closable discharge means for applying the counterpressure to the wad of yarn at the discharge end of the box so that the stuffing pressure is maintained substantially equal to the desired value.

This invention relates to the box-crimping of synthetic yarn and, more particularly, to a method and apparatus in which a yarn is forced into a stuifer `box against a wad of the yarn already crimped within the box, the yarn is crimped by the stuffing pressure acting on the yarn within the stuing box, crimped yarn is discharged from the box, and a counterpressure is simultaneously applied to the wad of yarn in such a manner that the stufiing pressure is maintained at a desired value.

A method similar to that of this invention is known. The known method generally aims at controlling the bpxcrimping process by measuring the amount of yarn present in the stuffer box or in an adjoining buffer chamber. This is often done by measuring the displacement of a discharge member, which is formed, for instance, by a hinged door. Displacement of the discharge member in this method adjusts, by way of a micro-switch, the speed of a pair of feed rollers which introduce the yarn into the box. The displacement may also serve to adjust the discharge rate of the box-crimped yarn. Although the known method may give reasonable results, the quality, more particularly the uniformity, of the yarn crimped by this method often is not satisfactory.

Advantageously, this invention provides a method and an apparatus for carrying out the method, that makes it possible in a simple way to improve the uniformity of the boxcrimping yarn.

Thus, this invention contemplates a method for boxcrimping synthetic yarn which comprises forcing a yarn into one end of a stuffer box against a wad of the yarn already crimped within the box, crimping the yarn at the stuing pressure found within the box, discharging crimped yarn from the wad of yarn at the other end of the box and simultaneously so applying to the wad of yarn a counterpressure, that acts in a direction opposite to the direction of travel of the yarn from the box, that the stuffing pressure remains substantially equal to a desired or reference value.

Also, the method of this invention is further char- ICC acterized in that the stuffing pressure within the stnffer box is measured and compared with the desired or reference value, a control signal indicative of the difference between the measured value and the reference value of the stuffing pressure is produced and the counterpressure is so varied as a function of the difference between the measured value and the reference Value in response to the control signal that the stui'ling pressure, as heretofore noted, remains substantially equal to the desired or reference value.

More specifically, in the box-crimping method of this invention, the yarn is forced by a pair of driven feed rollers into the feed end of the stuier box; the yarn is crimped and given a substantially zig-Zap form by the stutiing pressure acting on the yarn just downstream of the nip of the feed rollers and approximately at the beginning of the wad of yarn already crimped in the box; the crimped yarn leaves the stutter box at its discharge end via a closable discharge member or means, and the counterpressure is applied to the wad of yarn within the box by the discharge member.

According to the invention, it has been found that the stuffing pressure, or a quantity that is in a direct and fixed relationship thereto, may advantageously :be measured automatically and be compared automatically with the desired value, if desired, by way of a transmission system or means. With a preferred embodiment of the method of the invention, the desired or reference value of the stuffing pressure is kept practically constant. However, embodiments of the method may also be such that the desired or reference value of the stuffing pressure is adjustable. Alternatively, the desired or reference value of the stufling pressure may, with advantage, also be varied during operation of the crimping process.

This invention also is directed to an apparatus for carrying out the method according to the invention. This apparatus comprises a stuffer box having a feed end for insertion of a yarn to be crimped and a discharge end for discharge of crimped yarn therefrom, a pair of driven feed rollers for forcing a yarn into the feed end of the box against a wad of the yarn already crimped within the box, a closable discharge member or means at the discharge end for applying a counterpressure to the wad of yarn, a pickup means for measuring the stuffing pressure (or a quantity that is in a direct and fixed relationship thereto) in the stuffer box at the feed end at the point where the wad of yarn is about to be formed and for producing a signal indicative of this measure value, a control means for actuating the closable discharge means by adjusting an external load thereon in response to a control signal indicative of the difference between the measured value and a reference value of the stuffing pressure, and a transmission means for coupling the pickup means to the control means and for transmitting the control signal thereto, whereby the counterpressure required for maintaining the stuing pressure substantially equal to the reference value is applied to the wad of yarn at the discharge end by said discharge means.

The invention will be further described with reference to the accompanying schematic drawings in which:

FIG. 1 shows, partly in section and partly in elevation, an embodiment of the box-crimping apparatus according to the invention; and

FIG. 2 shows part of the apparatus of FIG. 1 in side elevation.

The box-crimping apparatus is provided with a pair of feed rollers 1 and 2, which are driven in the directions indicated by the arrows and are, for instance, pressed together in a known way by spring pressure. As a result, the yarn 3 to be crimped is forced into the stuifer box 4 in the direction indicated by the arrow. The stutfer box is formed by two walls and 6, which are in contact with the sides of the feed rollers 1 and 2, and by two walls 7 and 8, the top ends of which butt against the circumfen ential surfaces of the feed rollers 1 and 2, respectively. At its bottom end, the stutter box 4 may be closed to a varying extent by a closable discharge means in the form of a door 10, which is hingedly attached at 9 and which may apply a counter-pressure to the wad of yarn moving downwards through the stutfer box 4.

Provided in the wall 5 of the stutfer box, just downstream of the nip -11 of the feed rollers 1 and 2 and approximately at the beginning of the resulting wad of yarn, is a slot 12, Which locally weakens a portion of the wall 5. On the outer surface of the Wall 5 at the slot, there is provided -a pickup means 13, including a strain gauge. The strain gauge is connected to an appropriate electrical power source and serves to measure the dellection of the wall due to the stuflng pressure applied to the yarn. The electrical resistance of the strain gauge is a function of the deilection of the wall 5, which is in turn dependent on the magnitude of the stufling pressure. The signals transferred via the strain gauge are compared with a desired reference value. Advantageously, comparison may be within the transmission means 14. The diiference between the value measured by the strain gauge and the reference value is amplified in the transmission means 14. Subsequently, the difference gives rise to the formation of a control signal, which is transferred to the control means for the discharge means, which includes solenoid 15. As a result, the permanent magnet 16 is displaced in a desired manner for turning the hinged door on the shaft 9, so that the counterpressure applied to the Wad of yarn by the door 10 is varied to maintain the stung pressure at the desired reference value, i.e., the door is moved toward wall 6 to increase the pressure and is moved away from the Wall to decrease the pressure. After leaving the stuifer box, the crimped yarn is withdrawn from the box and may be wound in a known Way.

It will be appreciated, as heretofore noted, that the stuffing pressure may be measured directly or va quantity that is in a direct and fixed relationship to the stung pressure may be measured and used to control the counterpressure in accordance with this invention.

While the novel features of the invention have been shown and described and are pointed out in the appended claims, it is to be understood that various omissions, substitutions and changes in construction and arrangement of the features shown and described may be made Y 4 by those skilled in the art without departing from the spirt and scope of the invention.

What is claimed is:

1. An apparatus for the box-crimping of synthetic yarn which comprises a stuifer box having a Wall for confining the yarn to he crimped, said Wall having a deflectable portion therein, a feed end for the insertion of the yarn to be crimped and a discharge end for discharging crimped yarn therefrom, a pair of driven feed rollers for forcing a synthetic yarn into the feed end against a Wad of yarn already crimped within the box, a closable discharge means at the discharge end for applying a counterpressure to the wad of yam, a pickup means for measuring the deflection of said Wall portion at the feed end at the point where the wad of yarn is about to be formed, which is an indication of the stufling pressure acting on the yarn, and for producing a signal indicative of this measured value, a control means for actuating the closable discharge means in response to a control signal indicative of the difference between the measured value and a reference value of the stuthng pressure and a transmission means for coupling the pickup means to the control means and for transmitting the control signal thereto, whereby the counterpressure required for maintaining the stuflng pressure substantially equal to the reference value is applied to the wad of yarn at the discharge end by said discharge means.

2. The apparatus of claim 1, in which said pickup means includes a strain gauge which is positioned adjacent to said wall portion and which is connected to an electrical power source, the electrical resistance of the gauge being a function of the deilection of said wall portion caused by said stuing pressure whereby signals transmitted via said gauge are indicative of the magnitude of said stuing pressure.

References Cited UNITED STATES PATENTS 2,820,988 1/1958 Wegener 19-66 2,960,730 ll/ 1960 Shattuck 19-66 2,407,100 9/1946` Richardson 19-240 3,256,569 6/ 1966 Draving 19-240 XR 3,280,444 10/1966 Stanley 28-72.14

FOREIGN PATENTS 964,908 7/ 1964 Great Britain.

DORSEY NEWTON, Primary Examiner 

